Research Article
Condition-Based Maintenance Optimization for Motorized Spindles Integrating Proportional Hazard Model with SPC Charts
Table 1
Characteristics of four typical SPC charts.
| Feature | Monitored statistic | Control limits |
| Shewhart | | | MA | | | CUSUM | | | EWMA | | |
| | Monitored variable at t | | The mean of in-control data | | The standard deviation of in-control data | n | Control limit width | W | Moving average width | k | The slope of the lower arm | D | Distance typically set to 10 | λ | The weighted parameter, | UCL | Upper control limit | LCL | Lower control limit |
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